Re: [Xen-devel] [PATCH v3 01/41] lcoking/barriers, arch: Use smp barriers in smp_store_release()

2016-01-12 Thread Michael S. Tsirkin 
On Tue, Jan 12, 2016 at 08:28:44AM -0800, Paul E. McKenney wrote:
> On Sun, Jan 10, 2016 at 04:16:32PM +0200, Michael S. Tsirkin wrote:
> > From: Davidlohr Bueso 
> > 
> > With commit b92b8b35a2e ("locking/arch: Rename set_mb() to smp_store_mb()")
> > it was made clear that the context of this call (and thus set_mb)
> > is strictly for CPU ordering, as opposed to IO. As such all archs
> > should use the smp variant of mb(), respecting the semantics and
> > saving a mandatory barrier on UP.
> > 
> > Signed-off-by: Davidlohr Bueso 
> > Signed-off-by: Peter Zijlstra (Intel) 
> > Cc: 
> > Cc: Andrew Morton 
> > Cc: Benjamin Herrenschmidt 
> > Cc: Heiko Carstens 
> > Cc: Linus Torvalds 
> > Cc: Paul E. McKenney 
> > Cc: Peter Zijlstra 
> > Cc: Thomas Gleixner 
> > Cc: Tony Luck 
> > Cc: d...@stgolabs.net
> > Link: 
> > http://lkml.kernel.org/r/1445975631-17047-3-git-send-email-d...@stgolabs.net
> > Signed-off-by: Ingo Molnar 
> 
> Aside from a need for s/lcoking/locking/ in the subject line:
> 
> Reviewed-by: Paul E. McKenney 

Thanks!
Though Ingo already put this in tip tree like this,
and I need a copy in my tree to avoid breaking bisect,
so I will probably keep it exactly the same to avoid confusion.

> > ---
> >  arch/ia64/include/asm/barrier.h| 2 +-
> >  arch/powerpc/include/asm/barrier.h | 2 +-
> >  arch/s390/include/asm/barrier.h| 2 +-
> >  include/asm-generic/barrier.h  | 2 +-
> >  4 files changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/ia64/include/asm/barrier.h 
> > b/arch/ia64/include/asm/barrier.h
> > index df896a1..209c4b8 100644
> > --- a/arch/ia64/include/asm/barrier.h
> > +++ b/arch/ia64/include/asm/barrier.h
> > @@ -77,7 +77,7 @@ do {  
> > \
> > ___p1;  \
> >  })
> > 
> > -#define smp_store_mb(var, value)   do { WRITE_ONCE(var, value); mb(); } 
> > while (0)
> > +#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } 
> > while (0)
> > 
> >  /*
> >   * The group barrier in front of the rsm & ssm are necessary to ensure
> > diff --git a/arch/powerpc/include/asm/barrier.h 
> > b/arch/powerpc/include/asm/barrier.h
> > index 0eca6ef..a7af5fb 100644
> > --- a/arch/powerpc/include/asm/barrier.h
> > +++ b/arch/powerpc/include/asm/barrier.h
> > @@ -34,7 +34,7 @@
> >  #define rmb()  __asm__ __volatile__ ("sync" : : : "memory")
> >  #define wmb()  __asm__ __volatile__ ("sync" : : : "memory")
> > 
> > -#define smp_store_mb(var, value)   do { WRITE_ONCE(var, value); mb(); } 
> > while (0)
> > +#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } 
> > while (0)
> > 
> >  #ifdef __SUBARCH_HAS_LWSYNC
> >  #define SMPWMB  LWSYNC
> > diff --git a/arch/s390/include/asm/barrier.h 
> > b/arch/s390/include/asm/barrier.h
> > index d68e11e..7ffd0b1 100644
> > --- a/arch/s390/include/asm/barrier.h
> > +++ b/arch/s390/include/asm/barrier.h
> > @@ -36,7 +36,7 @@
> >  #define smp_mb__before_atomic()smp_mb()
> >  #define smp_mb__after_atomic() smp_mb()
> > 
> > -#define smp_store_mb(var, value)   do { WRITE_ONCE(var, value); 
> > mb(); } while (0)
> > +#define smp_store_mb(var, value)   do { WRITE_ONCE(var, value); smp_mb(); 
> > } while (0)
> > 
> >  #define smp_store_release(p, v)
> > \
> >  do {   
> > \
> > diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
> > index b42afad..0f45f93 100644
> > --- a/include/asm-generic/barrier.h
> > +++ b/include/asm-generic/barrier.h
> > @@ -93,7 +93,7 @@
> >  #endif /* CONFIG_SMP */
> > 
> >  #ifndef smp_store_mb
> > -#define smp_store_mb(var, value)  do { WRITE_ONCE(var, value); mb(); } 
> > while (0)
> > +#define smp_store_mb(var, value)  do { WRITE_ONCE(var, value); smp_mb(); } 
> > while (0)
> >  #endif
> > 
> >  #ifndef smp_mb__before_atomic
> > -- 
> > MST
> > 

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Re: [Xen-devel] [PATCH v3 01/41] lcoking/barriers, arch: Use smp barriers in smp_store_release()

2016-01-12 Thread Paul E. McKenney 
On Sun, Jan 10, 2016 at 04:16:32PM +0200, Michael S. Tsirkin wrote:
> From: Davidlohr Bueso 
> 
> With commit b92b8b35a2e ("locking/arch: Rename set_mb() to smp_store_mb()")
> it was made clear that the context of this call (and thus set_mb)
> is strictly for CPU ordering, as opposed to IO. As such all archs
> should use the smp variant of mb(), respecting the semantics and
> saving a mandatory barrier on UP.
> 
> Signed-off-by: Davidlohr Bueso 
> Signed-off-by: Peter Zijlstra (Intel) 
> Cc: 
> Cc: Andrew Morton 
> Cc: Benjamin Herrenschmidt 
> Cc: Heiko Carstens 
> Cc: Linus Torvalds 
> Cc: Paul E. McKenney 
> Cc: Peter Zijlstra 
> Cc: Thomas Gleixner 
> Cc: Tony Luck 
> Cc: d...@stgolabs.net
> Link: 
> http://lkml.kernel.org/r/1445975631-17047-3-git-send-email-d...@stgolabs.net
> Signed-off-by: Ingo Molnar 

Aside from a need for s/lcoking/locking/ in the subject line:

Reviewed-by: Paul E. McKenney 

> ---
>  arch/ia64/include/asm/barrier.h| 2 +-
>  arch/powerpc/include/asm/barrier.h | 2 +-
>  arch/s390/include/asm/barrier.h| 2 +-
>  include/asm-generic/barrier.h  | 2 +-
>  4 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/ia64/include/asm/barrier.h b/arch/ia64/include/asm/barrier.h
> index df896a1..209c4b8 100644
> --- a/arch/ia64/include/asm/barrier.h
> +++ b/arch/ia64/include/asm/barrier.h
> @@ -77,7 +77,7 @@ do {
> \
>   ___p1;  \
>  })
> 
> -#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); mb(); } 
> while (0)
> +#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } 
> while (0)
> 
>  /*
>   * The group barrier in front of the rsm & ssm are necessary to ensure
> diff --git a/arch/powerpc/include/asm/barrier.h 
> b/arch/powerpc/include/asm/barrier.h
> index 0eca6ef..a7af5fb 100644
> --- a/arch/powerpc/include/asm/barrier.h
> +++ b/arch/powerpc/include/asm/barrier.h
> @@ -34,7 +34,7 @@
>  #define rmb()  __asm__ __volatile__ ("sync" : : : "memory")
>  #define wmb()  __asm__ __volatile__ ("sync" : : : "memory")
> 
> -#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); mb(); } 
> while (0)
> +#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } 
> while (0)
> 
>  #ifdef __SUBARCH_HAS_LWSYNC
>  #define SMPWMB  LWSYNC
> diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
> index d68e11e..7ffd0b1 100644
> --- a/arch/s390/include/asm/barrier.h
> +++ b/arch/s390/include/asm/barrier.h
> @@ -36,7 +36,7 @@
>  #define smp_mb__before_atomic()  smp_mb()
>  #define smp_mb__after_atomic()   smp_mb()
> 
> -#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); 
> mb(); } while (0)
> +#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); 
> } while (0)
> 
>  #define smp_store_release(p, v)  
> \
>  do { \
> diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
> index b42afad..0f45f93 100644
> --- a/include/asm-generic/barrier.h
> +++ b/include/asm-generic/barrier.h
> @@ -93,7 +93,7 @@
>  #endif   /* CONFIG_SMP */
> 
>  #ifndef smp_store_mb
> -#define smp_store_mb(var, value)  do { WRITE_ONCE(var, value); mb(); } while 
> (0)
> +#define smp_store_mb(var, value)  do { WRITE_ONCE(var, value); smp_mb(); } 
> while (0)
>  #endif
> 
>  #ifndef smp_mb__before_atomic
> -- 
> MST
> 


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[Xen-devel] [PATCH v3 01/41] lcoking/barriers, arch: Use smp barriers in smp_store_release()

2016-01-10 Thread Michael S. Tsirkin 
From: Davidlohr Bueso 

With commit b92b8b35a2e ("locking/arch: Rename set_mb() to smp_store_mb()")
it was made clear that the context of this call (and thus set_mb)
is strictly for CPU ordering, as opposed to IO. As such all archs
should use the smp variant of mb(), respecting the semantics and
saving a mandatory barrier on UP.

Signed-off-by: Davidlohr Bueso 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: 
Cc: Andrew Morton 
Cc: Benjamin Herrenschmidt 
Cc: Heiko Carstens 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Tony Luck 
Cc: d...@stgolabs.net
Link: 
http://lkml.kernel.org/r/1445975631-17047-3-git-send-email-d...@stgolabs.net
Signed-off-by: Ingo Molnar 
---
 arch/ia64/include/asm/barrier.h| 2 +-
 arch/powerpc/include/asm/barrier.h | 2 +-
 arch/s390/include/asm/barrier.h| 2 +-
 include/asm-generic/barrier.h  | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/ia64/include/asm/barrier.h b/arch/ia64/include/asm/barrier.h
index df896a1..209c4b8 100644
--- a/arch/ia64/include/asm/barrier.h
+++ b/arch/ia64/include/asm/barrier.h
@@ -77,7 +77,7 @@ do {  
\
___p1;  \
 })
 
-#define smp_store_mb(var, value)   do { WRITE_ONCE(var, value); mb(); } 
while (0)
+#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } 
while (0)
 
 /*
  * The group barrier in front of the rsm & ssm are necessary to ensure
diff --git a/arch/powerpc/include/asm/barrier.h 
b/arch/powerpc/include/asm/barrier.h
index 0eca6ef..a7af5fb 100644
--- a/arch/powerpc/include/asm/barrier.h
+++ b/arch/powerpc/include/asm/barrier.h
@@ -34,7 +34,7 @@
 #define rmb()  __asm__ __volatile__ ("sync" : : : "memory")
 #define wmb()  __asm__ __volatile__ ("sync" : : : "memory")
 
-#define smp_store_mb(var, value)   do { WRITE_ONCE(var, value); mb(); } 
while (0)
+#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } 
while (0)
 
 #ifdef __SUBARCH_HAS_LWSYNC
 #define SMPWMB  LWSYNC
diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
index d68e11e..7ffd0b1 100644
--- a/arch/s390/include/asm/barrier.h
+++ b/arch/s390/include/asm/barrier.h
@@ -36,7 +36,7 @@
 #define smp_mb__before_atomic()smp_mb()
 #define smp_mb__after_atomic() smp_mb()
 
-#define smp_store_mb(var, value)   do { WRITE_ONCE(var, value); 
mb(); } while (0)
+#define smp_store_mb(var, value)   do { WRITE_ONCE(var, value); smp_mb(); 
} while (0)
 
 #define smp_store_release(p, v)
\
 do {   \
diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index b42afad..0f45f93 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -93,7 +93,7 @@
 #endif /* CONFIG_SMP */
 
 #ifndef smp_store_mb
-#define smp_store_mb(var, value)  do { WRITE_ONCE(var, value); mb(); } while 
(0)
+#define smp_store_mb(var, value)  do { WRITE_ONCE(var, value); smp_mb(); } 
while (0)
 #endif
 
 #ifndef smp_mb__before_atomic
-- 
MST


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